陶瓷粉体干压成型工艺参数优化的离散元模拟

摘要

通过建立氧化铋陶瓷粉体干压成型过程的离散元模型，研究了压力、加压速度、摩擦因数等工艺参数对成型后坯体孔隙率的影响，并与干压成型试验结果进行了对比。结果表明：压力、加压速度、摩擦因数等对坯体的压实性都具有明显影响；压力越大，加压速度越小，颗粒与颗粒之间及颗粒与模具壁之间的摩擦因数越小，则成型后坯体的孔隙率越小，压实性也越好；另外，在干压成型试验中，靠近上冲头处的颗粒粒径较小且均匀，而靠近下冲头处的颗粒粒径较大；这与模拟中坯体孔隙率随高度方向的变化趋势较为吻合。%The discrete element model of dry pressing molding for Bi2Oa ceramic powders was used to investigate the influences of processing parameters （such as pressure, compression speed, friction coefficient, etc. ） on the porosity of green body. The results were compared with those of dry pressing molding tests. The results show that there was a significant effect on the compaction of green body for pressure, compression speed and friction coefficient, etc. The greater the pressure, the smaller the compression speed, the smaller the friction coefficient between particles and between particles and die, the smaller the forming porosity of green body, the better the compactibility of the green body. In addition, small and uniform particles were close to the upper punch, while large particles were close to the lower punch during the dry-pressing experiments. It was consistent well with the trends of the porosity of green body in the direction of height in discrete element simulation.